Reality, perception, physics

Thoughts on Reality

An insubstantial pageant

The one thing we can be reasonably sure of is that what we see has nothing to do with reality. Physics tells us as much as that; that there are no things and there is no colour green. Visual information is delivered to the retina by photons fluctuating at varying frequencies. The photons are either reflected from or produced by ‘objects’, which can in their turn be understood as quantum particles held together by the charges of the electromagnetic force. Even when ‘objects’ are conceived of only as the electromagnetic binding of quanta, this exaggerates their reality; the second law of thermodynamics determines that the entropy or disorder of ‘objects’ can only increase, leading to their eventual dissolution. As is well known, the quanta are tiny as compared to the space between them. So the appearance we see of solid trees, plants, houses etc. is created in the brain, and is in fact an insubstantial pageant.

The neuroscience view

What neuroscience has taught us about the brain in recent years only goes to confirm the message of physics. Visual data enters via the interaction of photons with the retina, but the process of visual perception involves more than and more complexity than the eyes. It takes 300-500 milliseconds for the initial signal to work its way through to conscious perception, via a series of processes in the primary and then the higher visual cortices.

Separate visual streams

There is a partial division between the dorsal visual stream responsible for unconscious actions or reactions, and the ventral visual stream responsible for conscious perceptions. Further to this, neuroscience has detected areas in the higher visual cortex that are specialised in working on such ‘external’ features as colour and shape. There is a feed forward/feed back process between the higher and lower cortices in which the eventual outcome of perception is in effect edited in the light of past perceptions and experiences. As a result, what one individual perceives is not necessarily identical to what another individual perceives, although the input at the respective retinas is identical.

Thus the brain merely processes the quanta and fundamental forces ‘out there’ into an adaptive representation. The analogy might be the map of the London tube network. The two dimensional piece of paper with some coloured lines bears no resemblance to concrete tunnels, or metal rails and vehicles. However, it is brilliantly adaptive in the sense of helping passengers to navigate the network.

Reality and the quanta

Given this it is tempting to seek reality amongst the quanta that comprise the world ‘out there’. But there may be problems in conceiving of any of the quanta as representing a fundamental reality. Einstein’s discovery that mass was convertible into energy and vice versa gives the hint that the quanta are also an insubstantial pageant. The electrons that are responsible for most of the electromagnetic binding of matter can be annihilated in collisions with oppositely charged positrons. Both particles become a shower of photons which may at some point be reabsorbed by other quanta. In the opposite direction, interactions between quanta can pluck electrons possessed of both mass and charge out of the vasty deep of the vacuum; and the vacuum itself is not what it seems, being less a void and more a plenum, with photons that continually pass in and out of existence; these can achieve a less transient existence when exposed to energy such as the energy of interacting quanta.

More substantial effects would produce many quanta from the vacuum. This is hypothesised to happen when spacetime is sharply curved by gravity close to the event horizon of a black hole, and it is suggested that passengers on a spaceship accelerating close to the speed of light would see hot particles rushing towards them out of the vacuum. This was tested recently when an electron was accelerated to one quarter of the speed of light, and its energy struck particles out of the vacuum.

Three quarks for Mr Mark

Even the quarks (as in three quarks for Mr Mark), which make up the particles in the nucleus of the atom, comprise most of the non-dark mass of the universe, and cannot be isolated by modern science, are seen to be no more substantial than the electrons with oppositely charged quarks annihilating one another in a shower of photons.

Quantum properties

The specifically quantum nature of the quanta is even more notorious. When these particles are sufficiently isolated from their environment, they are not point particles at all, but extended as waves that can have effects in more than one location. Traditionally this is detected when individual quanta pass through two slits and form a wave-like interference pattern on a screen. The more unnerving version of this traditional two-slit experiment is when single quanta are sent one-at-a-time with significant gaps in time in between. The wave interference pattern still emerge, so somehow it seems that the earlier particles or the later particles or both know how to position themselves so that the interference pattern gradually emerges.

Be careful of entanglement

But more notorious than this is the occurrence of entanglement between quantum particles. In the 1930s Einstein sought to oppose the emerging version of quantum theory. The most serious challenge was the EPR experiment (actually a thought experiment) which showed that if the proposals of quantum theory were correct, some property of a quanta could be altered by a change to another quanta, even though the two particles were out-of-range of a signal travelling at the speed of light.

Einstein thought that this discredited quantum theory, but in 1982, a real, as opposed to a thought experiment, conducted by physicist, Alain Aspect, demonstrated that this in fact happens. Too much should not be made of entanglement vis- a-vis anomalous events; even an unorthodox thinker such as Rupert Sheldrake cautions against this. Both particles must maintain some form of isolation from their environment, and only the quantum property of spin can be transmitted. The mass and charge of particles remains bound by light-speed constraints.

Spacetime and fundamental reality

Where should we find reality in all this? There are basically two choices at the quantum level. Probably the majority of mainstream physicists would view the quanta as the fundamental reality, and argue that it is the quanta that create spacetime. The argument can run something like this. If there was only one particle in the universe, would you know whether it was moving or rotating? It is only by having more particles that one can make a judgement on relative movement, and from this point of view it is the existence of quanta that creates spacetime. There is nothing wrong with this view, and there is no obvious argument that refutes it.

However, the opposite view that spacetime is fundamental and effectively creates the quanta looks to solve quite a few problems. Such a view doesn’t place one outside the orthodoxy of science, but probably only in a minority within it. Following on from quantum theory in which everything is ‘quantised’ into separate entities, most scientists of both views think that spacetime is not a continuum, but is discrete in the form of some type of web or weave.

In the first place, if we go back to the argument at the beginning of this piece, as to visual perceptions being a creation of the brain that is nothing to do with reality, we saw that the quanta that make up ‘objects’ and the photons that project light from the ‘objects’ to the retina bear to resemblance to our visual perceptions. But the same is not entirely true for the spatial separation between objects. Our perception of spatial separations may be distorted to a greater or lesser extent, but we are not deceived in thinking that there are separations. Otherwise the reality would be a singularity. The tube maps representation of the distance between Leicester Square and West Finchley is probably way out-of-scale, but it is correct in suggesting that these places are spatially separated. The suggestion here is that space and spatial separation have a fundamental reality that the quanta do not possess.

In addition to this, the idea of a spacetime as a fundamental looks to solve some of the problems thrown up by quantum properties. The wave nature of the isolated quanta can be viewed as a wave in spacetime, something that fails to make sense in a more Newtonian view of particles. The wave may effectively extend in time as well as space with the position of particles undecided until decided by the arrival of other particles; this allows waves whose initiation is separated in time to combine in subsequent interference patterns. The problem of entanglement, which looks like a direct contradiction of the Newtonian concepts that we are all brought up on, is less of a problem if the quanta are waves in spacetime which are not constrained by the light-speed limitations of both mass and charge.

Bohm and Penrose

The fundamental spacetime concept is close to both the separate concepts of David Bohm and Roger Penrose. Bohm suggested that the two fundamental physics theories, quantum theory and relativity, which are not compatible with one another are underpinned by what he called the implicate order, a level which would include consciousness. Unfortunately he didn’t suggest any mechanism or evidence for this implicate order. Penrose was more specific in terms of a fundamental spacetime geometry, which could be accessed by a process called objective reduction, giving access to mathematical understanding and ultimately consciousness.